Not sure if I should post this in the ISS Q&A thread, but I have been asked about "the difference between the 'hybrid' and 'classic' probe-and-cone docking mechanisms" and realized I don't have a clue! The only reference I could find by Googling is a reference to Zvezda, the Service Module:

The aft docking port has a probe and cone docking mechanism to allow dockings by Progress resupply spacecraft and Soyuz piloted spacecraft. It also will be outfitted with an automated rendezvous and docking system. The forward docking ports all will have hybrid docking mechanisms to allow docking with the Zarya using the forward-facing port...

Is there an explanation or diagrams available of what these actually are?

http://www.hq.nasa.gov/office/pao/History/SP-4209/p172.htm etc... perhaps. That's the 'classic', AFAIK. I may be wrong with this exact picture, but the point is that the 'passive'/'active' mechanisms roles are fixed (target/docking spacecraft). An "androgynous" on the other hand (the 'hybrid' in this nomenclature) docking adapter system (the APAS for example) can have both sides act as 'active'/'passive' and interchanged as needed (there are quite a few links on that system)

The hybrid and classic docking systems are both probe and cone docking systems, the APAS-89 is an androgynous system. The differnce btween the classic and hybrid is size, hybrid is larger and is used to join modules together, all the front ports of Zvezda are hybrid ports. The smaller classic docking system is used to dock Soyuz and Progress vehicles. The rear ports of Zvezda and the nadir ports of Zarya and Pirs are this type. The front port of Zarya is an APAS.

You are completely right, I missed the probe mechanism reference, didn't realize the 'hybrid' is a specific term for the specific hardware, to me it just seemed to refer to the APAS as a description of the operation mode, sorry for the confusion.

You are completely right, I missed the probe mechanism reference, didn't realize the 'hybrid' is a specific term for the specific hardware, to me it just seemed to refer to the APAS as a description of the operation mode, sorry for the confusion.

"Hybrid" gets its name due to having the structural ring from the APAS and the probe-and-drogue mechanism from the "classic". As a result, APAS and Hybrid are hot-swappable provided the interface is pressurized. NASA had plans in 1997-2000 to convert the Zarya aft mechanism from Hybrid to APAS using an "FGB Pressure Dome" if required to dock the Interim Control Module. Fortunately Zvezda eventually launched and ICM was not required.-- JRF

The hybrid and classic docking systems are both probe and cone docking systems, the APAS-89 is an androgynous system. The differnce btween the classic and hybrid is size, hybrid is larger and is used to join modules together, all the front ports of Zvezda are hybrid ports. The smaller classic docking system is used to dock Soyuz and Progress vehicles. The rear ports of Zvezda and the nadir ports of Zarya and Pirs are this type. The front port of Zarya is an APAS.

APAS 89 is used in the PMA's to dock to the shuttle and the Zarya/PMA1 interface.

AFAIK, these are APAS-95 units. If there is a source that definitely states that these are APAS-89, I would be surprised.

AFAIK, the only difference between 89 and 95 is on the "active" side, so the difference should only affect the PMA-1 APAS, which (again, AFAIK) is the only active APAS on ISS (it was used exactly once, for the berthing of the FGB on STS-88). FGB and PMA-2/3 are passive APAS.-- JRF

APAS 89 is used in the PMA's to dock to the shuttle and the Zarya/PMA1 interface.

AFAIK, these are APAS-95 units. If there is a source that definitely states that these are APAS-89, I would be surprised.

AFAIK, the only difference between 89 and 95 is on the "active" side, so the difference should only affect the PMA-1 APAS, which (again, AFAIK) is the only active APAS on ISS (it was used exactly once, for the berthing of the FGB on STS-88). FGB and PMA-2/3 are passive APAS.

Please forgive my ignorance, but doesn't the 'androgynous' in the APAS refer to the interchangeability of the docking collars/mechanisms? As such, would the 'active'/'passive' distinction re: the APAS be a misnomer? Or is it that one can be re-configured into passive/active on demand? (still a bit confused about this one)

APAS 89 is used in the PMA's to dock to the shuttle and the Zarya/PMA1 interface.

AFAIK, these are APAS-95 units. If there is a source that definitely states that these are APAS-89, I would be surprised.

AFAIK, the only difference between 89 and 95 is on the "active" side, so the difference should only affect the PMA-1 APAS, which (again, AFAIK) is the only active APAS on ISS (it was used exactly once, for the berthing of the FGB on STS-88). FGB and PMA-2/3 are passive APAS.

Please forgive my ignorance, but doesn't the 'androgynous' in the APAS refer to the interchangeability of the docking collars/mechanisms? As such, would the 'active'/'passive' distinction re: the APAS be a misnomer? Or is it that one can be re-configured into passive/active on demand? (still a bit confused about this one)

It's not a misnomer. The term "Androgynous" only applies to the mechanical interface; in theory any APAS can be mounted to any other APAS. But one interface *must* be "active", with an extensible capture ring with capture latches. The passive side has neither an extensible ring nor capture latches, but it does have two gangs of active hooks, like the active side.

With non-androgynous systems like probe-and-drogue, you can only dock A->P, not A->A or P->P. With androgynous you can mount A->P or A->A, but you still can't do P->P.-- JRF

Ah, that's clear enough. Thanks much. This matter of precise terminology with regards to the APAS operation often comes up wrt dockings in other discussions, this has clarified it for me. Sorry for sidetracking the thread a bit.

Ah, that's clear enough. Thanks much. This matter of precise terminology with regards to the APAS operation often comes up wrt dockings in other discussions, this has clarified it for me. Sorry for sidetracking the thread a bit.

It was a good on-topic question, not a sidetrack at all. No apologies required.-- JRF

As a follow up, I get the impression from my reading that the follow onto APAS, various termed LIDS/ADBS/IDBS is basically an lightened APASwith a computer controlled electromagnetic latching system rather thanthe mechanical system APAS uses.

My understanding is that the electromagnetic latching system requiresless contact force to initiate capture than APAS, which uses (sprung?)mechanical latches. This in turn allows the whole structure to belighter, negating the need for lightweight 'Passive' versions withoutthe ring-extension mechanism. In effect all ADBS units are lightweight'Active' APAS units with magnetic latches (note that the two systemsare NOT compatible)

Thus all ADBS dockings are A->A (with only one unit used in the'Active' role?)

Also the two systems (APAS and ADBS) share aperture sizes etc. so amodule or spacecraft designed to mount one is relatively easy to modifyto mount the other (I presume the major issue is power and control forthe latches and extension system if ADBS is replacing anAPAS(Passive)). Hence there is no major design issue regarding earlyOrion capsules using an APAS, other than ADBS probably being lighter.

Rick

Logged

I am not interested in your political point scoring, Ad Hominem attacks, personal obsessions and vendettas. - No matter how cute and clever you may think your comments are.

Also the two systems (APAS and ADBS) share aperture sizes etc. so amodule or spacecraft designed to mount one is relatively easy to modifyto mount the other

I believe that APAS and probe/cone (as well as hybrid) have similar mounting requirements (ie aperture sizes and bolt patterns), although I have not seen this documented anywhere. Of course, Soyuz TM-16 flew with APAS-89, so its clear that its possible to substitute APAS for probe and cone, but I believe that swap-out of Russian docking systems is fairly easy - I would not be surprised if the bolt pattern for probe and cone were identical to APAS.